Torque measuring wrench



May 25, 1943. H. w. zmMn-:RMAN

TORQUE MEASURING vWlICi-i4 2 Sheets-Sheet 1 INVENTOR. .ZU/merma,

Filed March 18, 1940 Patented May 25, 1943 2,320,023 ToEQUE MEAsUmNG WRENCH Herman W. Zimmerman, Highland Park, Ill., as.-

signor to Automotive Maintenance Machinery Co., North Chicago, Ill., a corporation of Illinois Application March 18, 1940, Serial No. 324,499

6 Claims.

My invention relates to torque measuring wrenches and it has to do more particularly with wrenches of the foregoing character adapted for measuring the force or torque applied therethrough to work such as nuts, bolts, studs and the like.

One of the objects of my invention is to provide 'an improved wrench of the foregoing character which is of simple construction, is inexpensive to manufacture, may be assembled and disassembled easily and quickly, and which is adapted to perform its torque measuring function in a high-Y ly ecient manner.

Another object is to provide improved means for indicating, in a, wrench of the foregoing character, the force or torque applied to a piece of work.

Still another object is to provideY a wrench of the foregoing character having stay-set means for measuring the force or torque applied through the wrench to the work.

Another object is to provide pressure indicating means for a wrench of the foregoing character which is operable by relative movement of relatively movable wrench parts in one direction to indicate pressure applied and which, upon relative movement of such parts in an opposite direction, is released from the wrench parts andremains in its pressure indicating' condition to indicate the maximum pressure applied during the pressure applying operation, the arrangement being such that the wrench parts may be released under tension without imposing injurious strains and stresses on the indicating means.

A more specific object is to provide a torque measuring Wrench structure of the foregoing character which lincludes relatively movable wrench parts and indicating means coupled together in such a way that the indicating means is actuated by movement of the wrench parts in one direction to indicate pressure and is released from the wrench parts when they move in an opposite direction coupling means being provided by which an operative relation may be established between the indicating means-and the vnench parts and by which the indicating means may be set for pressure indication upon relative movement of the wrench parts in reverse directions.

Another object is to provide a torque measuring wrench having relatively movable parts and gage mechanism for measuring the relative movement of the parts to indicate pressure applied, which right-hand or left-hand direction, the coupling -means, in either instance, being adapted to cause actuation of the gage means when the wrench parts are moved in one direction and to disconnect the gage means from the wrench parts when the wrench is released after movement in one pressure applying direction or the other.

Other objects and advantages will become apparent as this description progresses and by reference to the drawings wherein- Figure 1 is a top plan view of one form of wrench embodying my invention, certain of the internal parts of the wrench being illustrated in dotted lines;

Fig. 2 is an enlarged longitudinal sectional view taken substantially on line 2-2 of Fig. 1;

Fig. 3 is a section taken substantially on line 3--3 of Fig. 2, the gage coupling means being shown in position to actuate the gage mechanism to indicate pressure; I

Fig. 4 is an enlarged vertical sectional view taken substantially on line 4-4 of Fig. 2;

Fig. 5 is a view taken substantially on line 5--5 of Fig. 4;

gage mechanism is adapted to be adjustably coupled to the wrench parts for operatively indicating pressure when the wrench is used in either a Fig. 6 is a fragmental sectional view taken substantially on line 6-6 of Fig. 5; and l Figs. 7 and 8 are fragmental views illustrating the gage coupling means in different positions it may assume during operation.

The wrench shown in the drawings includes a hollow head member I0 which supports a workengaging member Il (Figs. 1 and 2). The head member I0 has a cover plate I2 detachably secured thereto by screws or studs I 3 and it also has a handle I4 extending rearwardly beyond its hollow part. The work-engaging member II has a body I I*I rotatably carried by the head member I0 and its cover plate I2, and it is provided with a rigid arm I Ib extending rearwardly and radially from the axis thereof into the hollow part of the head member I0. 'I'he work-engaging member is further provided with an axial opening IIc (of square or other noncircular shape in cross section) for reception of an element (not shown) by which the wrench may be engaged with the work.

The head and work-engaging members I0 and Il are connected together by a spring bar I5 which yieldably opposes relative rotation thereof. The forward end of the spring bar I5 is rigidly connected to the arm IIb of the work-enl gaging member and its rear end is rotatably conried, as at I6, by the head member I0 and with which the spring bar I5 is slidably engaged, as at ISB.

The force or pressure applied through the wrench to the work is determined by measuring in terms of pressure or otherwise the extent of relative rotation of the head and work-engagingmembers a's permitted by said spring bar i5. To this end, I employ gage mechanism carried by the head member I8 and coupled to the Workengaging member I'I in such a manner that the gage mechanism is not only actuated by relative movement of the wrench parts to indicate the pressure but it stays set, so to speaks' in its pressure indicating condition, upon rellease of the Wrench, until manually reset to a normal nonpressure indicating condition.

The gage mechanism shown in the drawings includes an annular mounting'plate I1 xedly secured to the cover plate I2 by a plurality of screws I8. The annular mounting plate I1 roeil tatablyand detachably supports a dome-like 1 vcover I 9; and to this end, the peripheral edge of the plate I1 is provided with a plurality of spring-pressed balls 28 which seat in an annular groove 2I formed in the inner bottom edge p0rtion of the cover I9; A dial plate 22 having the same general contour as the inner wall of the cover I9 is rotatably supported upon the mounting plate I1 `Within the cover I8, the cover I9 being provided with a transparent Window 23 through which a graduated scale 24 on the dial plate 22 may be observed. The scale 24 is, preferably, graduated numerically in units indicating inch-pounds pressure, and the window 23 is provided with an indicating line with which the graduations of the scale 24 register as the dial 22 rotates to indicate any desired pressure condition. Any desired initial registration between the line 25 and the dial scale 24 may be effected by rotating the cover I9 relative to the dial.

The dial plate 22 is rotatably mounted upon the mounting plate I1 by a hub-like member 25. 'I'he dial is iixed to the upper end of the hub member '26 by confining the central portion of the same between the hub 28 and 'a washer 21, which Washer is clamped to the hub 25 by a member 28 having a threaded stem portion 28 passing through the washer 21 and engaging a threaded opening in the upper end of the hub 28. 'Ihe clamp member 28 is long enough to project upwardly and freely through an opening 29 in the central portion of the cover I9 where it receives a knurled finger button 38 secured to the member 28 by a screw 3 I. As willbe pointed out hereinafter, the finger button 38 may be manually rotated to,'in turn, rotate the dial 22 and thereby set the same to a predetermined initial operating position. 'I'his rotative adjustment oi' the dial 22, coupled with the rotative adjustment of the cover I9, provides a flexible means by which the gage mechanism may be easily and quickly set for accurate pressure indications when using the wrench in either a right-hand or left-hand direction to either tight-` en or loosen a piece of work.

The dial 22 (Figs. 2, 4 and 5) and its supporting hub 25 are rotated through relative movement of the work-engaging member II and the head member I8 as permitted by flexing of the spring bar I5 when pressure is applied to the work. To this end. the upper end of a shaft 32 is iixedly secured in the hub 25, which shaft extends freely and -rotatably downward through an opening 33 in the central, annular, thickened portion 34 of the mounting plate I1 where it supvbottom face of the mounting plate I1.

'Ihe mounting plate I1 (Figs. 4 and 5) is provided in its bottom face with a lateral slideway 39 which connects with the pinion recess 36 and, in this slideway, I mount a slide 48 having teeth 4I Awhich mesh with the teeth of the pinion 35. The slide 48 is further provided with a depending pin 42 which projects through an elongated slot 43 in a plate 43 which is secured to the bottom face of the plate portion 34 and closes the bottoms of the lateral slideway 38 and the pinion recess 35. With this arrangement, by sliding the plate 48 back and forth, the pinion 35 is actuated to rotate the dial 22;` and I accomplish movement of the slide plate 48 by coupling the same to the work-engaging member II.

To .the end last stated, I employ a plate-like coupling device 44 having its forward end iixedly secured to the inner end of the work-engaging arm IIb. The coupling plate 44 is of suiiicient length to extend rearwardly along and above the spring bar I5 to a point beneath the slide plate 48. The inner or free end of the plate 44 is forked providing fork arms or abutments 45* and 45h downwardly between which the plate carried pin 42 or pinion operating part extends. The fork arms 45a and 45h are spaced apart a distance considerablyy greater than the width of the pin 42 so that the arms 45-and 45b may be independently engaged by the pin 42 but both may not be engaged simultaneously. By so spacing apart the fork arms as stated, I provide an arrangement wherein the gage mechanism may be manually set for actuation upon relative movement of the wrench parts in applying pressure to a piece of work, and when the wrench parts are released after such pressure application, the gage mechanism is uncoupled from the wrench parts so that it remains set at the maximum pressure condition reached in setting up the work. Thus, the operator may easily and accurately checkl the pressure applied after the wrench has been released from pressure.

In the use of the structure described, assumingthat a piece of work is to be tightened by the application of, say, 400 inch-pounds pressure applied in a right-hand direction, the linger adjustment k'nob 38 is rotated in a counterclockwise direction as far as possible-or to an extent sufiicient to move the slide plate 48 and its pin 42 .into engagement with the fork abutment arm 45, as indicated in Fig. 3. The -cover I8 is then rotated to make its indicating line 25 coincide with the zero line of the dial scale 24 (Fig. 1). With the parts in these positions and the workengaging member II engaged with the work, the

v.work-engaging and head members II and Il moves relatively as soon as suiilcient pressure is applied to overcome the initial tension of the spring bar I5. As this action takes place, the rack bar 48 is moved in a direction to rotate the vpinion 35 clockwise, in turn, rotating the dial 22 and its scale 24 clockwise relative to the cover mark 25, as illustrated in Fig. 7. 'I'his action takes place so long as pressure is applied and when the work is set up to the desired pressure (400 inch-pounds, for example), as indicated by the dial 22, the pressure application is stopped and the parts are permitted to return to their normal positions under the influence of the spring bar .I5. It will be seen that the wrench members I8 and AII move relatively in an opposite direction as'fl'gjhey return to normal, thereby reversing the foregoing operation and freeing or uncoupling the pin 42 from the fork abutment.

45* and uncoupling the relatively movable members from the gage mechanism, as shown in Fig. 8.

When the gage mechanism is thusly uncoupled, the'dial and its operating mechanism are yieldably retained in their pressure indicating condition so that the operator may carefully check the pressure application with the wrench parts at rest. Specically, for this purpose, I employ a pair of spring members 46 and 41 (Figs. 4 and 6) located on opposite sides of and engaging the dial hub 26.. Each spring member includes a base portion 48 secured, at 49, to the mounting plate I1, and an uptsanding spring arm 50 which engages the outer wall of the hub 26 under tension. In this Way, the dial 22 is retained in a pressure indicating condition (Fig. 8) until it is readjusted through the ringer knob 30 and the foregoing operation is repeated.

If it should be desired to measure the pressure applied in a left-hand operation of the wrench, as when loosening a piece of work, the foregoing operation is carried out except that the finger knob 30 is first rotated in a clockwise direction to operably engage theslide pin 42 with the fork abutment 45h. The cover I9 is rotated to set its mark 25 to the zero point and the pressure applied in a left-hand or loosening direction.

I believe that the operation and advantages of my invention will be readily understood from the foregoing description. The wrench is of the constant moment arm type and is adapted to perform its intended functions in a highly eflicient manner. A single piece of work may be tightened in a precision manner and successive pieces of work may be set up in identical fashion. One

may denitely determine the exact amount of v pressure required to loosen any particular piece of Work so that it may, if desired, be reapplied in an accurate manner. The use of the wrench in any position is facilitated because the pressure used in application of the work can always be checked even though the user could not accurately observe the pressure indication at the time of application. It will be appreciated that in the use of prior torque wrenches, the observing of the gage markings at different angles may result in diierent readings although the same pressure is applied. My invention avoids that. Also, the coupling means that I employ positively avoids the imposition of strains and stresses on the gage mechanism when the wrench is released under tension, so that sensitive gage mechanism may be safely employed, and the life of the device as a whole is lengthened.

I claim:

1. A torque measuring wrench comprising a pair of relatively rockable members, one being relative movement of said relatively rockable members in a direction to move said actuating member toward the engaged abutment actuates said indicating element, the arrangement being such that said actuating member is moved away from and uncoupled from said abutment upon relative movement of said relatively rockable members in a direction the opposite of that employed to actuate said indicating element, and spring means for retaining said indicating element in its pressure indicating condition when said actuating member is uncoupledfrom the op- -K erative one of said abutments.

2. A torque measuring wrench comprising a head member, a work-engaging member rockably connected therewith, spring means yieldably opposing relative rock movement of said members, and means for indicating pressure applied which includes a movable indicating element carried by said head member, means carried by said head member for moving said element including a depending part and connections between said part and said element, a coupling device having one end secured to said work-engaging member with its other end free and formed with abutment elements spaced apart a distance greater than the width of said depending part which is disposed therebetween, and means for manually ad- I justing said depending part to engage oneor the other of said abutment elements, the arrangement being such that when said members are rocked relatively in one direction with said depending part engaged with one of said abutment elements said indicating element is actuated to indicate pressure and when said members are rocked relatively in an opposite direction said depending part is disconnected from said abutment elements, and means for yieldably retaining said indicating element in its pressure indicating condition upon disconnection of said parts.

3. A torque measuring wrench comprising a head member, a work-engaging member rockably connected thereto, means yieldably resisting relative rock movement of said members, and

. means for measuring the extent of said rock movementin terms of pressure applied which includes a movable indicating element carried by one of said members and having an operating part, and a coupling element carried by the other adapted for engagement with the work, means yieldably opposing, relative movement of said members, and means for indicating the pressure applied through said members which includes a movable indicating element carried by one of said relatively rockable members, an indicating element actuating member carried "by said one member and adjustable with said element to one or the other of two initial operating positions, means for coupling said actuating memberto the other of said relatively rockable members for movement of said actuating member thereby upon relative movement of said relatively rockable Y members, said coupling means having a pair of laterally spaced abutments adapted to be engaged by said actuating member when it is adjusted to either of its said initial operating positions so that of said members and having a pair of spaced varms between which said operating part is disposed, said arms being spaced apart such a distance that said operating part may engage one or the other thereof but not both simultaneously, and means for adjusting said indicating element in a direction to engage its operating part with one or the other of said arms, the arrangement being such that when said operating part is engaged with one of said arms and said members are moved relatively in one direction said indicating element will be moved to indicate a pressure condition and when said members are moved relatively in an opposite direction said one coupling arm and operating part are disengaged, and means for yieldably retaining said indicating element in its pressure indicating condition to indicate the pressure condition attained until further adjustment of the same by saidv adjusting means.

4. A torque measuring wrench comprising a pair of relatively movable members, means for yieldably opposing relative movement of said members, and means for measuring the extent of relative movement of said members in terms of pressure applied which comprises a gage unit supported by one of said members and including a rotatable indicating element, a rack and pinion drive for said indicating element, a rack operating member projecting from said rack and pinion drive, means for adjusting said indicating element independently of its operation through said rack and pinion drive, and a coupling device having one end secured to the other oi.' said relatively movable members with-a free end fork providing spaced abutments between which is disposed said rack operating part, said abutments being spaced apart a distance substantially greater than the width of said rack operating part so that one or the other, but not both simultaneously, of said abutments, may be engaged with said operating part, the arrangement being such that when one of said abutments is engaged with said operating part and said relatively movable members are rocked in one direction said rack and pinion drive is actuated to move said indicating element and when said members are rocked in an opposite direction said previously engaged abutment is released from said rack operating part disconnecting the coupling device from the indicating element, and means for yieldably retaining said indicating element in its pressure indicating condition subject to adjustment by said adjusting means.

5. A torque measuring wrench comprising a pair' of relatively rockable members, spring means between and yieldably opposing rock movement of said members, and means for indicating pressure applied which includes a gradiated dial rotatably carried by one of said members, a rotatable cover for said dial having a window with an indicating means registrable with the calibrations of said dial, means directly associated with said dial for rotating the same including an operating part therefor, and a coupling device carried by the other of said members and adapted to be engaged by said operating part for rotation of said dial upon relative movement of said members in one direction, and adapted upon relative movement of said members in an opposite direction to become disengaged from said operating part, means for initially adjusting said operating part into operative engagement with said coupling device, and means for retaining said dial in its pressure indicating condition upon disconnection of said coupling device and operating part.

6. indicating mechanism for a torque measuring wrench having a head member and a workengaging member displaceable relative to each other in a rotative direction and having a yieldable connection therebetween yieldably opposing relative rotational displacement, which comprises an indicator unit adapted to be carried by the head member and having an indicating element, an adjustable member having a depending part for actuating said indicating eleiaent, a coupling member adapted to be secured at one end to the work-engaging member with its other end free and provided with abutments spaced apart a greater distance than the width of said depending part which is disposed therebetween, the arrangement being such that when said actuating member is adjusted to engage said depending part with" one of said `abutments and the head and work-engaging members are displaced rotatively in one direction said indicating element is actuated and when the head and work-engaging members are displaced in an opposite direction said depending part is disconnected from the previously engaged one of said abutments, and means for yieldably retaining said indicating element in an indicating condition when said depending part and abutment are disengaged.

HERMAN W. ZIMMERMAN. 

